Question

Which one of the following is oxidised by $Mn{O_2}$?
A.${C_6}{H_5}C{H_2}OH$
B.$C{H_2} = CHC{H_2}CHC{H_3}$
C.$C{H_3}CH = CHC{H_2}C{H_3}$
D.$C{H_3}C{H_2}C{H_2}OH$

Answer 1

Hint: Oxidation is a chemical reaction in which a compound either loses electrons or gains oxygen in a reaction. $Mn{O_2}$ is an inorganic compound which is used as a catalyst for oxidation reaction and is a mild oxidising agent which oxidises benzylic alcohols to aldehydes.

Complete answer:
Oxidation is the process in which a molecule loses electrons to gain noble gas configuration. When the oxidation state of an atom in a molecule is increased, then oxidation takes place. The process in which a molecule gains electrons is called reduction and it takes place when the oxidation state of an atom decreases. If in a reaction oxygen is a reactant then the compound which gains oxygen is said to be oxidized and the other compound which is usually oxygen is said to be reduced. In a reaction where both oxidation and reduction takes place is known as a redox reaction.
Thus, we now know that a compound which easily gains oxygen or loses electrons gets oxidized. Oxidation is used for various commercial purposes. Ammonia is oxidized to produce nitric acid which is used in fertilizers. Rapid oxidation is the process of rapid burning of a compound in the presence of moisture/water and oxygen which liberates heat and light. Manganese dioxide $Mn{O_2}$ is an inorganic compound which is used as a catalyst in the process of rapid oxidation. It is black coloured solid which is a metal oxide. It is used in batteries which are used in automobiles.
For the given question we know that $Mn{O_2}$is a mild oxidising agent which oxidises primary and secondary benzylic alcohols. The benzylic alcohols are oxidised to form aldehydes.
${C_6}{H_5}C{H_2}OH$ is benzylic alcohol which is oxidised by $Mn{O_2}$ to aldehyde.
${C_6}{H_5}C{H_2}OH + Mn{O_2} + {H^ + } \to {C_6}{H_5}COH + M{n^{2 + }} + {H_2}O$

Thus, the correct option is (A)

Note: When alkanes are oxidised they give carbon dioxide and water as a product through a free-radical mechanism. When an alkane is oxidised completely then the energy released is called the heat of combustion. In alkanes the more branched isomer is more stable than the less branched structures.